Yes, one day my mum was turned into a pig. Read this tale of parental deception, and it might tell you a few things about young children's complex relationship to reality, fiction, and 'jokes'.

I was four and a half years old when I was first sent to a holiday skiing camp somewhere in the Alps. It wasn't the first time I was separated from my parents, and though it wasn't the best thing ever I was dealing with it fine.

One afternoon, the Head of the holiday camp found me in tears under a table. I wouldn't budge, so she had to drag me out, but I stayed resolutely silent and it took time and several adults to get me, eventually, to tell them what was wrong.

What was wrong was that I'd just received a postcard from my dad. I'd been a fluent reader for over a year by then so I hadn't asked anyone to read the postcard to me, and that was what the postcard said:

'Hello darling! hope you're having fun! guess what - a naughty fairy's turned Mummy into a pig! but don't worry, I feed her every day. Love, Dad'

The front of the postcard was, adequately, a picture of a cute little pink piggy.

And I'd believed every single word of it. Even though I was already a proficient reader, I'd been completely unable to recognise that my dad was actually joking.

Of course my parents got a furious phone call at work from the Head, who said they were completely mental to send letters like that to their four-year-old, and then my dad (who was by then in tears with laughter) was told off like there was no tomorrow by my mum, who felt extremely bad, especially as she'd told him not to do it because I might not get the humour, but then had eventually let him do it anyway.

It took a phone call from my mum assuring and reassuring me that she was still a human before I stopped crying and agreed to get up and go skiing with the other kids. Then everything was fine.

That's a pretty good example, I think, of a 'child not understanding humour' anecdote with relatively tragic consequences (if mostly funny in hindsight). Ironically enough, if I hadn't been a good reader by then this postcard would have been read to me by an adult, who would have explained the joke. But because no one could imagine that a letter from a nice daddy would contain such completely inappropriate humour, they left the four-year-old reader to her own unsophisticated reading skills, and to her own risk and peril.

The day my mum was turned into a pig, I probably learnt more about the dangers of reading and imagination than any other day of my life until then.